Many internal combustion engines, such as those operating on the four-stroke principle, are provided with at least one intake valve and at least one exhaust valve. The intake and exhaust valves are disposed in intake and exhaust passages respectively. They are actuated to open and close the passages in order to control the flow of air and fuel into a combustion chamber of the engine and the flow of exhaust gases out of the combustion chamber. Various mechanisms exist to actuate the movement of the valves.
One such mechanism includes a camshaft, at least one cam, a cam follower, and a spring. The camshaft is disposed for rotation in the cylinder head assembly of the engine. The least one cam is disposed on the camshaft for rotation therewith. The cam follower has an end abutting an end of a valve. Rotation of the camshaft causes the cam to engage the cam follower such that the cam follower rotates and moves the valve to an open position where the passage associated with the valve fluidly communicates with the combustion chamber. The spring biases the valve back to a closed position, thus preventing fluid communication between the passage and the combustion chamber.
The valves sometimes need to be replaced or cleaned. However, in the mechanism described above, since cam follower abut the ends of the valves, access to the valves can be difficult.
Also, in order to prevent premature wear of the cam and/or the cam follower due to friction between these two parts, lubricant needs to be supplied between the two parts. However, it can be difficult to provide the elements necessary to supply the lubricant since the space in the cylinder head assembly is generally limited.
Therefore, there is a need for an internal combustion engine having a camshaft, a cam, and a cam follower providing access to the valves.
There is also a need for a internal combustion engine where lubricant is supplied between the cam and the cam follower.